Apparatus and method for sensing high precision signal using infrared light

ABSTRACT

A high precision signal sensing system and method using an infrared light is provided. The high precision signal sensing system may receive, from a light emitting device, a plurality of lights including a first light and a second light, may measure intensities of the first light and the second light, and may measure a light emitting intensity of the light emitting device based on an intensity difference between the measured light receiving intensities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/280,825, filed Oct. 25, 2011, which claims the priority benefit ofKorean Patent Application No. 10-2010-0138939, filed on Dec. 30, 2010,in the Korean Intellectual Property Office, the disclosure of which isincorporated herein by reference.

BACKGROUND

1. Field

One or more example embodiments of the present disclosure relate to amethod that may discretely transmit, using a transmitter, signals basedon different directionalities or may discretely receive, using areceiver, signals based on different directionalities in differentdirections, and may measure a directional signal to be used forestimating a target object including the transmitter, selectively usingat least one of intensities measured with respect to the receivedsignals and an intensity difference between the intensities. Forexample, when the transmitted signal is light, example embodimentsrelate to a method that may precisely measure a light having a highsignal-to-noise ratio (SNR) to be used for estimating a light emittingdevice, based on an intensity difference between a plurality of lightsemitted from the light emitting device.

2. Description of the Related Art

Conventionally, technologies for estimating a three-dimensional (3D)location and direction of a mobile object or a target object have beenutilized for sensing a motion of an object or a target object, such as,a human body, an animal, and the like, in a 3D space, using huge,expensive motion capturing equipment in various fields includinggraphics, animation industries, and the like.

One of the methods of estimating 3D location and direction is a methodthat uses infrared light. The method of estimating the 3D location anddirection is limited to measuring an intensity of an infrared lightsignal received from a light emitting device and estimating, with arelatively low reliability, the 3D location and direction using themeasured intensity of the infrared light signal.

Therefore there is a desire for a method of measuring a signal having ahigh signal-to-noise radio (SNR), to improve estimation of the 3Dlocation and direction.

SUMMARY

One or more example embodiments of the present disclosure may include ahigh precision signal sensing system that may emit, using a lightemitting device, a first light and a second light having differentdirectionalities or may receive, with different directionalities, lightsemitted from the light emitting device, may measure light receivingintensities of the first light and the second light, may selectively usemeasured light receiving intensities and an intensity difference betweenthe measured intensities and thus, may precisely measure a signal havinga high signal-to-noise ratio (SNR) as a signal to be used for estimatingthe light emitting device.

The foregoing and/or other aspects are achieved by providing a highprecision signal sensing system, the system including a receiver toreceive a signal from a transmitter, and a measuring device to measurean intensity with respect to a first signal and a second signal, thefirst signal and the second signal being classified based on a distanceand a receiving direction, and to measure a directional signal to beused for estimating a target object including the transmitter, based onat least one of the measured intensities and an intensity differencebetween the intensities.

The foregoing and/or other aspects are achieved by providing a highprecision signal sensing system, the system including a light receivingdevice to separately receive, as a first light and a second light, alight emitted from a light emitting device by changing a directionalityor a light receiving direction, and a measuring device to measure afirst light receiving intensity with respect to the first light and asecond light receiving intensity with respect to the second light, andto measure a directional light to be used for estimating the lightemitting device, based on an intensity difference between the firstlight receiving intensity and the second light receiving intensity.

The foregoing and/or other aspects are achieved by providing a method ofsensing a high precision signal, the method including receiving, by alight receiving device, a light emitted from a light emitting device,measuring a light receiving intensity with respect to a first light anda second light, the first light and the second light being classifiedbased on a distance and a light receiving direction, and measuring adirectional light to be used for measuring the light emitting device,based on at least one of the measured light receiving intensities and anintensity difference between the measured light receiving intensities.

In addition, a non-transitory computer-readable storage medium encodedwith computer readable code comprising a program for implementing themethod of sensing a high precision signal.

The foregoing and/or other aspects are achieved by providing a highprecision signal sensing system that includes a receiver made up of a aplurality of light receiving units having different directionalities andreceiving a first light signal and a second light signal from atransmitter and a measuring device. The measuring device measures anintensity with respect to the first light signal and the second lightsignal, the first light signal and the second light signal beingclassified based on at least one of a distance from the transmitter anda receiving direction, and to measure a directional signal to be usedfor estimating a target object based on at least one of the measuredintensities of the first light signal and the second light signal and anintensity difference between the intensities.

Additional aspects of embodiments will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of embodiments, taken inconjunction with the accompanying drawings of which:

FIG. 1 illustrates a high precision signal sensing system;

FIG. 2 illustrates a light emitting directionality of an infrared lightsignal of which a light receiving intensity varies based on the lightemitting directionality of the infrared light signal;

FIG. 3 illustrates a light emitting directionality and a light receivingdirectionality of an infrared light signal;

FIG. 4 illustrates an example of a high precision signal sensing system;

FIG. 5 illustrates an example of a light receiving intensity withrespect to a directional light of a light receiving unit;

FIGS. 6A through 6C illustrate other examples of a high precision signalsensing system;

FIG. 7 illustrates a system that estimates a location and a directionusing a high precision signal sensing system;

FIG. 8 illustrates a parameter to be used for calculation that estimatesa three-dimensional (3D) location and direction, when two lightirradiators are utilized;

FIG. 9 is a flowchart illustrating a high precision signal sensingmethod.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to the like elements throughout. Embodiments aredescribed below to explain the present disclosure by referring to thefigures.

A transmitter may be a device for transmitting a signal, and, inembodiments, the transmitter may include at least one light irradiatorthat emits a signal in a form of light based on differentdirectionalities.

A receiver may be a device for receiving a signal transmitted from thetransmitter, and, in embodiments, the receiver may include at least onelight receiving unit that receives a signal in the form of light basedon different directionalities or may include at least one lightreceiving unit that receives, based on the same directionality, thesignal in the form of light in different reception directions.

In embodiments, one of or both the transmitter and the receiver maytransmit and receive signals based on different directionalities or indifferent directions and thus, a purpose of measuring a signal having ahigh signal-to-noise radio (SNR) may be obtained.

In embodiments, the light receiving unit may be included in a lightreceiving device including a light sensing function, and the lightirradiator may be included in a target object of which a location and adirection is to be estimated.

The receiver, that is, one of the elements included in a high precisionsignal sensing system, may perform a function of receiving signals fromthe transmitter. The signals may be order-classified as a first signaland a second signal based on a distance from the transmitter or areception direction. Depending on embodiments, signals transmitted froma plurality of transmitters may be order-classified as the first signaland the second signal.

The transmitter may enable respective signals transmitted from thetransmitter to have different directionalities, and may separatelytransmit the signals as the first signal and the second signal based onvarious schemes, such as a time-division scheme that independentlytransmits each signal at a predetermined time, a coding scheme, such asa modulation, a scheme that transmits respective signals using differentoptical wavelengths, and the like. The high precision signal sensingsystem may include at least one transmitter.

The receiver may receive the first signal and second signal havingdifferent directionalities and thus, may enable a measuring device toprecisely measure a directional signal based on intensities ofrespective signals, an intensity difference, and the like.

The high precision signal sensing system may include at least onereceiver. When a single receiver is included in the system, the receivermay receive the first signal and the second signal by changing areception direction.

When a plurality of receivers is included in the system, the receiversmay receive the first signal and the second signal based on differentdirectionalities, respectively, or the receivers arranged to have thesame directionality may receive, in different reception directions, thefirst signal and the second signal, respectively.

The high precision signal sensing system may receive signals havingdifferent directions from the target object and thus, may provide anenvironment that selectively uses a signal having a relatively high SNRwhen a location and a direction of the target object is estimated.

The measuring device may measure an intensity with respect to the firstsignal and the second signal, the first signal and the second signalbeing classified based on a distance from the transmitter and areception direction, and may measure a directional signal to be used forestimating the target object including the transmitter, based on atleast one of the measured intensities and an intensity differencebetween the measured intensities.

The measuring device may measure a signal corresponding to the intensitydifference as the directional signal, in a directionality where a firstintensity measured with respect to the first signal or a secondintensity measured with respect to the second signal is less than theintensity difference.

In an area of a directionality where respective intensities of thesignals are less than a predetermined threshold, a signal correspondingto an intensity difference between the signals, as opposed to therespective signals, may be measured as a signal to be used forestimating the target object.

Conversely, in a directionality where the first intensity or the secondintensity is greater than or equal to the intensity difference, themeasuring device may measure a signal corresponding to the firstintensity or the second intensity, as the directional signal.

In an area of a directionality where respective intensities of thesignals are greater than the intensity difference between the signals, asignal having a high resolving power may be selectively measured as asignal to be used for estimating the target object. In this example, asignal of which an intensity rapidly decreases as a directionalityincreases may be determined as the signal having the high resolution.

For example, in an area of a directionality where the first intensity orthe second intensity is greater than the intensity difference, that is,in a directionality of less than or equal to 1 radian, the measuringdevice may select a signal having a high resolving power among the firstintensity and the second intensity, that is, a signal of which anintensity rapidly decreases as a directionality increases.

Conversely, in an area of a directionality where the first intensity orthe second intensity is less than the intensity difference, themeasuring device may measure a signal corresponding to the intensitydifference as a directional signal in the area of the directionality.

One or more example embodiments will be described with reference to anexample that transmits signals in a form of light.

FIG. 1 illustrates a high precision signal sensing system 100.

Referring to FIG. 1, the high precision signal sensing system 100 mayinclude, for example, a light receiving device 110 and a measuringdevice 120.

The light receiving device 110 may receive, from a light emitting device130, a plurality of lights including a first light and a second light.In this example, the light emitting device 130 may include at least onelight irradiator, for example, a first light irradiator 131, up to ann^(th) light irradiator 132. The light receiving device 110 may alsoinclude at least one light receiving unit, for example, a first lightreceiving unit 111, up to an n^(th) light receiving unit 112. The lightirradiator may be, for example, a light emitting diode (LED), and mayemit an infrared light signal. The light receiving unit may be, forexample, a photodiode, and may sense the emitted infrared light signal.

When a number of light receiving units included in the light receivingdevice 110 is relatively smaller than a number of light irradiatorsincluded in the light emitting device 130, for example, when the numberof light irradiators is two and the number of light receiving units isone, the light receiving device 110 may receive, using the single lightreceiving unit, a first light and a second light emitted from therespective light irradiators.

In this example, the respective light irradiator in the light emittingdevice 130 may be arranged in the same direction and may form fieldshaving different directionalities. When the respective light irradiatorsare arranged in the same direction, the light emitting device 130 mayemit a plurality of lights in the same direction, and, since therespective light irradiators form fields having differentdirectionalities, the light emitting device 130 may emit the pluralityof lights having different intensities. The light emitting device 130may separately emit lights, as a first light and a second light, basedon a time division scheme, a coding scheme, an optical wavelength, andthe like.

When the number of light receiving units included in the light receivingdevice 110 is greater than the number of the light irradiators includedin the light emitting device 130, for example, when the number of lightirradiators is one and the number of light receiving units is two, thelight emitting device 110 may use the two light receiving units andrespectively receive a first light and a second light emitted from thesingle light irradiator.

In this example, the light receiving units included in the lightreceiving device 110 may be arranged in the same direction and may formfields having different directionalities. The light receiving device 110may arrange the light receiving units in the same direction to receive aplurality of lights in the same direction, and, since the respectivereceiving units form fields having different directionalities, the lightreceiving device 110 may receive the plurality of lights havingdifferent intensities.

For another example, the light receiving units included in the lightreceiving device 110 may be arranged in different directions and mayform fields having the same directionality. Even through the respectivelight receiving units form fields having the same directionality, thelight receiving device 110 may receive a plurality of lights havingdifferent intensities, since the respective light receiving units arearranged in different directions.

When the plurality of lights are received, the measuring device 120 maymeasure a light receiving intensity with respect to the first light andthe second light, the first light and the second light being classifiedbased on a distance from the transmitter 130 and a reception direction,and may measure, based on an intensity difference between the lightreceiving intensities, a directional light to be used for estimating thelight emitting device 130 corresponding to a target object.

For example, the measuring device 120 may measure a light correspondingto the intensity difference between the first light receiving intensityand the second light receiving intensity, as the directional light ofthe light emitting device 130, in an area of a directionality where afirst light receiving intensity measured with respect to the first lightor a second light receiving intensity measured with respect to thesecond light is less than the intensity difference. In this example, thelight corresponding to the intensity difference may have a high SNRsince noise included in the first light may offset noise included in thesecond light. Therefore, the measuring device 120 may measure thedirectional signal based on the light that corresponds to the intensitydifference and that has the high SNR and thus, may provide anenvironment that may precisely estimate the target object using a lightmaintaining a signal intensity of a predetermined level.

Conversely, in an area of a directionality where the first lightreceiving intensity measured with respect to the first light or thesecond light receiving intensity measured with respect to the secondlight is greater than or equal to the intensity difference between thefirst light receiving intensity and the second light receivingintensity, the measuring device 120 may measure a light corresponding tothe first light receiving intensity or the second light receivingintensity, as the directional signal. For example, the measuring device120 may select, from among the first light receiving intensity and thesecond light receiving intensity, an intensity that has a highresolution, that is, an intensity that rapidly decreases as adirectionality increases, and may measure a light corresponding to theselected intensity may be measured as the directional signal to be usedfor estimating the light emitting device 130.

When the light irradiators included in the light emitting device 130 arearranged in the same direction and form fields having differentdirectionalities, the measuring device 120 may measure a plurality oflight receiving intensities based on reception directions or emittingdirections and distances between the light receiving units and therespective light irradiators, under a condition that the formed fieldshave intersected with fields associated with respective light receivingunits included in the light receiving device 110.

For another example, when the light receiving units included in thelight receiving device 110 are arranged in the same direction and mayform fields having different directionalities or when the lightreceiving units included in the light receiving device 110 are arrangedin different directions and may form fields having the samedirectionality, the measuring device 120 may measure a plurality oflight receiving intensities, based on reception directions or emittingdirections and distances between the light receiving units and therespective light irradiators, under a condition that the formed fieldsintersect fields associated with respective light irradiators includedin the light emitting device 130.

The measuring device 120 may measure the directional signal to be usedfor estimating the light emitting device 130 based on a light receivingdirectionality of the light receiving device 110 and a light emittingdirectionality of the light emitting device 130, in addition to anintensity difference between light receiving intensities associated withrespective emitted lights. In this example, the light receivingdirectionality may be a property that changes a light receivingintensity based on a directionality of a light receiving unit thatreceives an emitted light, and the light emitting directionality may bea property that changes a light receiving intensity based on adirectionality of a light irradiator that emits a light.

FIG. 2 illustrates a light emitting directionality of an infrared lightsignal of which a light receiving intensity varies based on a lightemitting direction of the infrared light signal.

Referring to FIG. 2, a light receiving intensity of the infrared lightsignal may vary based on a direction angle of a light irradiator, thatis, based on a directionality of the infrared light signal at apredetermined distance. Referring to FIG. 2, an x-axis and a y-axis maydenote measuring angles at which a light receiving unit measures thelight irradiator, and a z-axis may denote an intensity of the emittedinfrared light signal.

FIG. 3 illustrates a light emitting directionality and a light receivingdirectionality of an infrared light signal.

Referring to FIG. 3, comparison between light receiving intensities of Aand B may show that a light receiving intensity of an infrared lightsignal varies based on a light emitting direction angle θ of a lightirradiator. The light receiving intensity of the infrared light signalmay be affected by a light receiving direction angle ψ that correspondsto a direction where a light receiving unit receives the infrared lightsignal.

An intensity of a signal measured based on a distance between the lightirradiator and the light receiving unit may satisfy Equation 1.

$\begin{matrix}{I \propto \frac{I}{r^{2}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, I may denote the measured intensity of the signal, and rmay denote the distance between the light irradiator and the lightreceiving unit.

An intensity of a signal measured based on a directionality of the lightirradiator may satisfy Equation 2.

I∝ cos(κθ)  [Equation 2]

In Equation 2, I may denote the measured intensity of the signal, k maydenote a parameter indicating an attenuation property of the lightirradiator, and a direction angle of the irradiator.

An intensity of a signal measured based on a directionality of the lightreceiving unit may satisfies Equation 3.

I∝ cos(λψ)  [Equation 3]

In Equation 3, I may denote the measured intensity of the signal, λ maydenote a parameter indicating an attenuation property of the lightreceiving unit, and ψ may denote a direction angle of the lightreceiving unit.

An intensity of a signal measured based on the distance between thelight irradiator and the light receiving unit, the directionality of thelight irradiator, and the directionality of the light receiving unit,may be expressed as Equation 4.

$\begin{matrix}{I = {\alpha \; {{\cos \left( {\kappa \; \theta} \right)} \cdot \frac{1}{r^{2}} \cdot {\cos \left( {\lambda \; \psi} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

In Equation 4, I may denote the measured intensity of the signal, r maydenote the distance between the light irradiator and the light receivingunit, α may denote a scale factor that is based on properties of thelight irradiator and the light receiving units, k may denote theparameter indicating an attenuation property of the light irradiator, θmay denote the direction angle of the light irradiator, λ may denote theparameter indicating the attenuation property of the light receivingunit, and ψ may denote the direction angle of the light receiving unit.

FIG. 4 illustrates an example of a high precision signal sensing system400.

Referring to FIG. 4, the high precision signal sensing system 400 mayreceive, using a single light receiving device 401, two lights emittedfrom two light irradiators 411 and 412 that are arranged in the samedirection in a light emitting device 410. In this example, two lightirradiators 411 and 412 may form fields having differentdirectionalities and may emit two lights having different intensities.Accordingly, the high precision signal sensing system 400 may receivetwo lights having different intensities.

The high precision signal sensing system 400 may measure, using the twolights having different light receiving intensities, a directionalsignal to be used for estimating the light emitting device 410. In anarea of a directionality where a first light receiving intensitymeasured with respect to a first light or a second light receivingintensity measured with respect to a second light is greater than orequal to an intensity difference between the first light receivingintensity and the second light receiving intensity, the high precisionsignal sensing system 400 may measure a light corresponding to the firstlight receiving intensity or the second light receiving intensity as adirectional signal in the corresponding area. In this example, the highprecision signal sensing system 400 may select an intensity of a lightemitted from a light irradiator having a relatively high resolution fromamong the first light receiving intensity and the second light receivingintensity and thus, may selectively measure an emitted light of which alight receiving intensity sensitively varies based on a change in adirectionality.

Conversely, in an area of a directionality where the first lightreceiving intensity or the second light receiving intensity is less thanthe intensity difference, the high precision signal sensing system 400may measure a light corresponding to the intensity difference as adirectional signal in the corresponding area.

FIG. 5 illustrates an example of a light receiving intensity withrespect to a directional light of a light receiving unit.

Referring to FIG. 5, in an area 501 of a directionality where a firstlight receiving intensity measured with respect to a first light or asecond light receiving intensity measured with respect to a second lightis greater than or equal to an intensity difference between the firstlight receiving intensity and the second light receiving intensity, ahigh precision signal sensing system may measure a light correspondingto the first light receiving intensity of a light irradiator having arelatively high resolution.

In an area 502, of a directionality where the first light receivingintensity or the second light receiving intensity is less than theintensity difference, the high precision signal sensing system mayselectively measure a light corresponding to the intensity difference.

Accordingly, since noise is offset, the high precision signal sensingsystem may use a signal of which an SNR is at least a predeterminedlevel and thus, may provide an environment that precisely estimates adistance and a direction of the light emitting device, that is, a targetobject.

FIGS. 6A through 6C illustrate other examples of a high precision signalsensing system.

Referring to FIG. 6A, a high precision signal sensing system 600 mayreceive, using two light receiving units 601 and 602, two lights emittedfrom a single light irradiator 611 included in a light emitting device610. The two light receiving units 601 and 602 may be arranged in thesame direction and may have different directionalities. In this example,the two receiving units 601 and 602 may form fields having differentdirectionalities and may separately receive two lights having differentintensities. In this example, the two lights having differentintensities may be separately transmitted, based on a time divisionscheme, a modulation scheme, an optical wavelength, and the like,respectively.

Referring to FIG. 6B, a high precision signal sensing system 620 mayreceive, using two light receiving units 621 and 622, two lights emittedfrom two light irradiators 631 and 632 arranged in the same direction inthe light emitting device 630. The two light receiving units 621 and 622may be arranged in the same direction and may have differentdirectionalities. In this example, two light irradiators 631 and 632 mayform fields having different directionalities, and may emit two lightshaving different intensities. The two light receiving units 621 and 622may form fields having different directionalities and may receive twolights having different intensities, respectively.

Referring to FIG. 6C, a high precision signal sensing system 640 mayreceive, using two light receiving units 641 and 642, two lights from asingle light irradiator 651 included in the light emitting device 650.The two light receiving units 641 and 642 may have the samedirectionality and may be arranged in different directions. Even thoughthe two light receiving units 641 and 642 form fields having the samedirectionality, the two light receiving units 641 and 642 may receivetwo lights having different intensities, respectively, since the twolight receiving units 641 and 642 are arranged in different directions.

A high precision signal sensing system may be variously configured, andmay measure a signal having a reliable SNR of at least a predeterminedlevel using different light receiving intensities with respect to anemitted light and thus, may precisely estimate a light emitting device.

FIG. 7 illustrates a system that estimates a location and a directionusing a high precision signal sensing system. In this example, alocation and direction estimating system 700 that estimates a locationand a direction may include the high precision signal sensing system.

Referring to FIG. 7, the location and direction estimating system 700may estimate a location (x, y, z) and a direction (φ, θ, ψ) of a lightemitting device, based on an intensity varying based on a distance or alight receiving direction with respect to a light received by a lightreceiving unit, for example, light receiving units 701, 702, and 703,and based on a light receiving directionality and a light emittingdirectionality. A location and direction estimating method of thelocation and direction estimating system 700 will be described withreference to FIG. 8.

FIG. 8 illustrates a parameter that may be used for a calculation thatestimates a three-dimensional (3D) location and direction, when twolight irradiators are utilized.

Referring to FIG. 8, unit direction vectors directed by the lightirradiators 711 and 712 and the light receiving unit 701 may be defined,with respect to a global coordinate system, as {right arrow over(a)}=(x_(a), y_(a) z_(a)), {right arrow over (b)}=(x_(b), y_(b), z_(b)),{right arrow over (s_(n))}=(x_(sn), y_(sn), z_(sn)), respectively. Adirection vector indicating a displacement from light irradiators 711and 712 to the light receiving unit 701 may be defined as {right arrowover (d_(n))}=(x_(dn), y_(dn), z_(dn)).

An angle between {right arrow over (d)}_(n) and each of {right arrowover (a)} and {right arrow over (b)} may be θ_(an) and θ_(bn), and, whenλ=1 in Equation 4, an intensity of a light received by a light receivingunit, for example, the light receiving units 701, 702, and 703 may beexpressed as Equation 5 and Equation 6.

$\begin{matrix}{I_{na} = {\alpha \; {{\cos \left( {\kappa \; {\cos^{- 1}\left( \frac{\overset{\rightarrow}{a} \cdot \overset{\rightarrow}{d}}{\overset{\rightarrow}{d}} \right)}} \right)} \cdot \frac{1}{{\overset{\rightarrow}{d}}^{2}} \cdot \frac{{- {\overset{\rightarrow}{s}}_{n}} \cdot \overset{\rightarrow}{d}}{\overset{\rightarrow}{d}}}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

In Equation 5, I_(na) may denote an intensity of a light emitted fromthe first light irradiator 711, which is received by an n^(th) lightreceiving unit.

$\begin{matrix}{I_{nb} = {\alpha \; {{\cos \left( {\kappa \; {\cos^{- 1}\left( \frac{\overset{\rightarrow}{b} \cdot \overset{\rightarrow}{d}}{\overset{\rightarrow}{d}} \right)}} \right)} \cdot \frac{1}{{\overset{\rightarrow}{d}}^{2}} \cdot \frac{{- {\overset{\rightarrow}{s}}_{n}} \cdot \overset{\rightarrow}{d}}{\overset{\rightarrow}{d}}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 6, I_(nb) may denote an intensity of a light emitted fromthe second light irradiator 712, which is received by the n^(th) lightreceiving unit.

When lights from the two light irradiators 711 and 712 are sequentiallyreceived within a short time or the lights are received based ondifferent frequencies, information associated with Equation 5 andEquation 6 may be discretely obtained. Therefore, each of the lightreceiving units 701, 702, and 703 may obtain two equations.

When the three light receiving units 701, 702, and 703 are used, sixequations may be obtained with respect to a location and a directionassociated with the light emitting device 710.

When {right arrow over (a)}, {right arrow over (b)}, and {right arrowover (d)}_(n) are obtained, the location and the direction may becalculated. Therefore, when nine unknown quantities corresponding tocomponents of the direction vectors are obtained, the location and thedirection may be calculated. In this example, {right arrow over (a)} and{right arrow over (b)} may be unit vectors and thus, may have a sizeof 1. A relative location relation between {right arrow over (a)} and{right arrow over (b)} may be given in advance and thus, threeadditional equations may be given.

Accordingly, the nine known quantities may be calculated from the nineequations based on an optimization scheme and the like. In this example,when a number of light receiving units increases, calculation may bebased on a normalization that minimizes an error.

When the location and direction estimating system 700 includes two lightirradiators 711 and 712, a location (x, y, z) and a direction (φ, θ, ψ)may vary based on the number of the light receiving units, as shown inTable 1. In this example, x, y, and z may denote a 3D coordinates, φ maybe a roll based on a z axis, θ may denote a pitch based on an x axis,and ψ may denote a yaw based on a y axis.

TABLE 1 Number of units Light Light emitting device Light receivingLocation Direction irradiator unit x y z φ θ ψ 2 3 ∘ ∘ ∘ ∘ ∘ ∘ 2 2 ∘ ∘ xx ∘ ∘

Referring to Table 1, when the location and direction estimating system700 has two light irradiators 711 and 712 and three light receivingunits 701, 702, and 703, the location and direction estimating system700 may estimate a 3D location (x, y, z) and three axis directions, thatis, roll(φ), pitch(θ), and yaw(ψ), associated with the light emittingdevice 710.

The estimation may be performed in the same manner, when the number ofthe light irradiators and the number of light receiving units areopposite to the above case. When the number of light irradiators isthree and the number of light receiving units is two, the location anddirection estimating system 700 may estimate the 3D location (x, y, z)and the three axis directions, that is, roll (φ), pitch (θ), and yaw(ψ), associated with the light emitting device 710.

Referring to Table 1, when the location and direction estimating system700 includes two light irradiators and two light receiving units, andthe roll (φ) among the three axis directions of the light emittingdevice 710 is fixed, the location and direction estimating system 700may estimate a location on a two-dimensional (2D) plane of the lightemitting device 710 and directions, that is, pitch (θ) and yaw (ψ), onthe 2D plane of the light emitting device 710

FIG. 9 illustrates a high precision signal sensing method.

Referring to FIG. 9, in operation 901, a high precision signal sensingsystem may receive a light from a light emitting device. The highprecision signal sensing system may discretely receive lights as a firstlight and a second light based on a distance between the light emittingdevice and the light receiving device, a light receiving direction, andthe like.

The high precision signal sensing system may variously receive emittedlights.

For example, the high precision sensing system may receive, using asingle light receiving unit, two lights having different intensities,which are emitted from two light irradiators having differentdirectionalities.

The high precision sensing system may receive, using two light receivingunits, two lights emitted from at least one light irradiator. The twolight receiving units may be arranged in the same direction and may havedifferent directionalities. The light receiving unit may receive twolights with different intensities because the intensities of the twolights grow to be different from each other due to the differentdirectionalities.

The high precision signal sensing system may receive, using two lightreceiving units, two lights emitted from at least one light irradiator.The two light receiving units may be arranged in different directionsand may have the same directionality. The light receiving units mayreceive, with different intensities, lights emitted from the lightirradiator by changing reception directions.

In operation 903, the high precision signal sensing system may measurelight receiving intensities of a first light and a second light, thefirst light and the second light being classified based on a distanceand a light receiving direction.

In this example, the light receiving intensities with respect to thefirst light and the second light may be different from each other.

In operation 905, the high precision signal sensing system may measure adirectional signal to be used for estimating the light emitting device,based on at least one of the measured light receiving intensities and anintensity difference between the light receiving intensities.

In a directionality where the first light receiving intensity or thesecond light receiving intensity is greater than or equal to theintensity difference, the high precision signal sensing system maymeasure a light corresponding to the first light receiving intensity orthe second light receiving intensity as the directional signal to beused for estimating the light emitting device. For example, the highprecision signal sensing system may measure a light associated with alight irradiator having a relatively high resolution, among lightscorresponding to the first light receiving intensity and the secondlight receiving intensity.

In a directionality where the first light receiving intensity or thesecond light receiving intensity is less than the intensity difference,the high precision sensing system may selectively measure a lightcorresponding to the intensity difference. In this example, the lightcorresponding to the intensity difference may have a high SNR sincenoise included in the first light offsets noise included in the secondlight. Accordingly, the high precision signal sensing system mayselectively measure a light having a high SNR based on a change indirectionality.

In addition, the location and direction estimating system that utilizesthe high precision signal sensing system may more precisely estimate thelocation or the direction associated with the light emitting devicecorresponding to a target object.

The method according to the above-described embodiments may be recordedin non-transitory computer-readable media including program instructionsto implement various operations embodied by a computer. The media mayalso include, alone or in combination with the program instructions,data files, data structures, and the like. Examples of non-transitorycomputer-readable media include magnetic media such as hard disks,floppy disks, and magnetic tape; optical media such as CD ROM discs andDVDs; magneto-optical media such as optical discs; and hardware devicesthat are specially configured to store and perform program instructions,such as read-only memory (ROM), random access memory (RAM), flashmemory, and the like.

Examples of program instructions include both machine code, such asproduced by a compiler, and files containing higher level code that maybe executed by the computer using an interpreter. The described hardwaredevices may be configured to act as one or more software modules inorder to perform the operations of the above-described embodiments, orvice versa. Any one or more of the software modules described herein maybe executed by a dedicated processor unique to that unit or by aprocessor common to one or more of the modules. The described methodsmay be executed on a general purpose computer or processor or may beexecuted on a particular machine such as the high precision signalsensing system described herein.

Although embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spirit ofthe disclosure, the scope of which is defined by the claims and theirequivalents.

What is claimed is:
 1. A high precision signal sensing system, thesystem comprising: a receiver to receive a first signal and a secondsignal emitted from a transmitter; and a measuring device to measure anintensity with respect to the first signal and the second signal and toestimate at least one of a location and direction of a target objectcomprising the transmitter based on at least one of the measuredintensities of the first signal and the second signal and an intensitydifference between the measured intensities, wherein the measuredintensities of the first signal and the second signal depend on at leastone of a receiving direction at the receiver, an emitting direction atthe transmitter and a distance between the transmitter and the receiver.2. The system of claim 1, wherein the measuring device estimates atleast one of the location and the direction of the target object bymeasuring a directional signal based on at least one of the measuredintensities and the intensity difference.
 3. The system of claim 2,wherein, the measuring device measures, as the directional signal, asignal corresponding to the intensity difference in a directionalitywhere a first intensity or a second intensity is less than the intensitydifference, the first intensity being measured with respect to the firstsignal and the second intensity being measured with respect to thesecond signal.
 4. The system of claim 2, wherein the measuring devicemeasures, as the directional signal, a signal corresponding to a firstintensity or a second intensity in a directionality where the firstintensity or the second intensity is greater than or equal to theintensity difference, the first intensity being measured with respect tothe first signal and the second intensity being measured with respect tothe second signal.
 5. The system of claim 1, wherein, when thetransmitter is a light irradiator that transmits the first signal andthe second signal based on different directionalities, in a form oflight, the measuring device estimates at least one of the location andthe direction of the target object based on a first light receivingintensity measured with respect to a first light corresponding to thefirst signal, a second light receiving intensity measured with respectto a second light corresponding to the second signal, and an intensitydifference between the first light receiving intensity and the secondlight receiving intensity.
 6. The system of claim 5, wherein the lightirradiator separately emits the first light and the second light basedon at least one of a time division scheme, a coding scheme, and anoptical wavelength.
 7. The system of claim 1, wherein, when the firstsignal and second signal are in a form of light, the receiver receives,based on different directionalities, a first light corresponding to thefirst signal and a second light corresponding to the second signal, orreceives, based on the same directionality, the first light and thesecond light in different receiving directions; and the measuring deviceestimates at least one of the location and the direction of the targetobject based on at least one of a first light receiving intensitymeasured with respect to the first light, a second light receivingintensity measured with respect to the second light, and an intensitydifference between the first light receiving intensity and the secondlight receiving intensity.
 8. The system of claim 1, wherein themeasuring device measures the intensity further based on adirectionality associated with the receiver or a directionalityassociated with the transmitter.
 9. A high precision signal sensingsystem, the system comprising: a light receiving device to separatelyreceive, as a first light and a second light, a light emitted from alight emitting device in different directionalities or differentreceiving directions; and a measuring device to measure a first lightreceiving intensity with respect to the first light and a second lightreceiving intensity with respect to the second light, and to estimate atleast one of a location or direction of the light emitting device, basedon at least one of the first light receiving intensity, the second lightreceiving intensity, and an intensity difference between the first lightreceiving intensity and the second light receiving intensity.
 10. Thesystem of claim 9, wherein the measuring device estimates at least oneof the location and the direction of the light emitting device bymeasuring a directional light based on at least one of the first lightreceiving intensity, the second light receiving intensity, and theintensity difference.
 11. The system of claim 10, wherein the measuringdevice performs: measuring, as the directional light, a lightcorresponding to the intensity difference, when the first lightreceiving intensity or the second light receiving intensity is less thanthe intensity difference; and measuring, as the directional light, alight corresponding to the first light receiving intensity or the secondlight receiving intensity, when the first light intensity or the secondlight intensity is greater than or equal to the intensity difference.12. A method of sensing a high precision signal, the method comprising:receiving a first signal and a second signal emitted from a transmitter;measuring an intensity with respect to the first signal and the secondsignal; and estimating at least one of a location or direction of thetarget object comprising transmitter based on at least one of themeasured intensities of the first signal and the second signal and anintensity difference between the measured intensities, wherein themeasured intensities of the first signal and the second signal depend onat least one of a receiving direction at the receiver, an emittingdirection at the transmitter and a distance between the transmitter andthe receiver.
 13. The method of claim 12, wherein the estimating of atleast one of the location and the direction of the target objectestimates at least one of the location and the direction of the targetobject by measuring a directional signal based on at least one of themeasured intensities of the first signal and the second signal and theintensity difference.
 14. The method of claim 13, wherein the measuringof the directional signal comprises: measuring, as the directionalsignal, a signal corresponding to the intensity difference in adirectionality where a first intensity measured with respect to thefirst signal or a second intensity measured with respect to the secondsignal is less than the intensity difference.
 15. The method of claim13, wherein the measuring of the directional signal comprises:measuring, as the directional signal, a signal corresponding to a firstintensity or a second intensity in a directionality where the firstintensity measured with respect to the first signal or the secondintensity measured with respect to the second signal is greater than orequal to the intensity difference.
 16. The method of claim 12, wherein,when the transmitter is a light irradiator that transmits the firstsignal and the second signal based on different directionalities, in aform of light, estimating of at least one of the location and thedirection of the target object estimates at least one of the locationand the direction of the target object based on a first light receivingintensity measured with respect to a first light corresponding to thefirst signal, a second light receiving intensity measured with respectto a second light corresponding to the second signal, and an intensitydifference between the first light receiving intensity and the secondlight receiving intensity.
 17. The method of claim 16, wherein the lightirradiator separately emits the first light and the second light basedon at least one of a time division scheme, a coding scheme, and anoptical wavelength.
 18. The method of claim 12, wherein, when the firstsignal and second signal are in a form of light, the receiving of thefirst signal and the second signal receives, based on differentdirectionalities, a first light corresponding to the first signal and asecond light corresponding to the second signal, or receives, based onthe same directionality, the first light and the second light indifferent receiving directions; and the estimating of at least one ofthe location and the direction of the target object estimates at leastone of the location and the direction of the target object based on atleast one of a first light receiving intensity measured with respect tothe first light, a second light receiving intensity measured withrespect to the second light, and an intensity difference between thefirst light receiving intensity and the second light receivingintensity.
 19. A method of sensing a high precision signal, the methodcomprising: separately receiving, as a first light and a second light, alight emitted from a light emitting device in different directionalitiesor different receiving directions; measuring a first light receivingintensity with respect to the first light and a second light receivingintensity with respect to the second light; and estimating at least oneof a location or direction of the light emitting device based on atleast one of the first light receiving intensity, the second lightreceiving intensity, and an intensity difference between the first lightreceiving intensity and the second light receiving intensity.
 20. Anon-transitory computer-readable storage medium encoded with computerreadable code comprising a program for implementing the method of claim12.